NAME
Enbugger - Enables the debugger at runtime.
SYNOPSIS
my $ok = eval { ...; 1 };
if ( not $ok ) {
# Oops! there was an error! Enable the debugger now!
require Enbugger;
Enbugger->stop;
}
DESCRIPTION
Allows the use of the debugger at runtime regardless of whether your
process was started with debugging. This is useful if you would like to
add hooks so the debugger is loaded on some kind of event or UNIX signal
or if for some reason you're having difficulty running your program with
debugging turned on at compile time.
INSTALLATION
To install this module type the following:
perl Makefile.PL
make
make test
make install
USING THE DEBUGGER
Loading the debugger
Loading the debugger at process start time works just like normal.
perl -d ...
You can also load the debugger at runtime:
use Enbugger;
Enbugger->load_debugger;
You can load a specific debugger:
use Enbugger;
Enbugger->load_debugger( 'perl5db' );
You can specific a default debugger:
$Enbugger::DefaultDebugger = 'perl5db';
Or...
use Enbugger 'perl5db';
Unloading the debugger
You wish. There is no implemented way to unload the debugger. Here's how
you'd do it if you wanted to implement this feature.
# Set the various C pointers set by Perl_init_debugger to NULL
# Clear the DB:: package. Beware of the "DB" and "sub" functions. If
you ever load another debugger again you'll need to ensure you have
at least stub functions left or you could suffer a fatal, deadly
death.
# Change all "dbstate" B::COP nodes back to be "nextstate" ops.
GETTING INTO THE DEBUGGER
Programatically
Call the public class method "Enbugger->stop". At a minimum, it will
just request that your current debugger stop execution.
If needed, it'll go as far as loading a debugger.
An example
if ( ... ) {
# an unlikely occurance I'd like to manually inspect if or when
# it happens.
Enbugger->stop;
}
On %SIG events
If you load the Enbugger::OnError module, you can use unhandled
exceptions or UNIX signals as break points. In addition, loading the
debugger is deferred until your signal or exception is triggered.
I like using this with both die() and SIGUSR1 handled enough that both
are the default for handling.
use Enbugger::OnError;
use Enbugger::OnError qw( __DIE__ USR1 ); # equivalent
A program using the above line will trigger a break point whenever an
unhandled die() occurs or whenever the USR1 signal is received. To use
other signals, just specify them at the use().
use Enbugger::OnError qw( USR1 USR2 INT HUP );
An example
Here's a quick example of breaking into a long running program to see
what it's doing.
At one terminal:
bash$ perl -MEnbugger::OnError -e 'while(1) {}'
At a separate terminal:
bash$ ps ax | grep perl
12850 pts/1 R 0:01 perl -MEnbugger::OnError -le while(1){}
12852 pts/1 R+ 0:00 grep perl
bash$ kill -USR1 12850
Back at the original perl program:
Loading DB routines from perl5db.pl version 1.3
Editor support available.
Enter h or `h h' for help, or `man perldebug' for more help.
Received signal USR1 at -e line 1
eval {...} called at -e line 1
Enbugger::OnError::(/home/jbenjore/src/Enbugger/blib/lib/Enbugger/OnError.pm:90):
90:
DB<1> T
$ = Enbugger::OnError::ExceptionHandler('USR1') called from -e line 1
$ = eval {...} called from -e line 1
DB<1> q
bash$
PUBLIC API
Enbugger has a public API where you as the user can trigger the debugger
from your code or affect which debugger is loaded.
CLASS->stop
Stops execution and signals your debugger. Loads a debugger with
"CLASS->load_debugger" if one hasn't been loaded yet.
CLASS->load_debugger( DEBUGGER )
CLASS->load_debugger
Loads your requested debugger. Defaults to using
$Enbugger::DefaultDebugger if you don't specify a debugger.
If a debugger has already been loaded, either returns silently if
the current debugger is what you requested or throws an exception if
you requested a different debugger.
$Enbugger::DefaultDebugger
The default debugger. This is "perl5db" unless you change it.
CLASS->write( TEXT )
Writes some thing to the console or wherever is appropriate for your
current debugger.
CLASS->DEBUGGER_CLASS
Returns the class name for the currently loaded debugger class.
If no debugger has been loaded yet, this contrives to load the
default debugger.
PLUGGABLE DEBUGGERS
Enbugger supports registering debuggers. Any debugger intended to be
used must be registered first. The default, proper behavior is to
register all possible debuggers.
Registered debuggers
The following is a list of all default, registered debuggers. So far
only the perl5db.pl debugger has received any testing.
perl5db
This is the default perl debugger. See also Enbugger::perl5db and
perl5db.pl.
Registering your own debugger
While I've attempted to register some debuggers by by default, you may
need to write your own Enbugger::$foo class to register your own
debugger. Currently there is no way to use an unknown debugger without
first writing an Enbugger subclass.
CLASS->register_debugger( DEBUGGER )
Register a debugger with Enbugger.
Required methods
You must implement the following methods.
CLASS->_stop
Your debugger must implement a "_stop" method. This method will be
called by the Enbugger->stop method. When this method is called, you
should stop the current process and invoke your debugger.
CLASS->_load_debugger
Your debugger must implement a "load_debugger" method. It will be
called when your debugger should be loaded. Your method is
responsible for loading the debugger.
CLASS->_write( TEXT )
Your debugger must implement a "_write" method. This method should
accept text to log to the console or whatever is appropriate.
UTILITY FUNCTIONS
CLASS->load_source
Loads the source code for the program.
CLASS->load_file( FILE )
Loads the source code for a specific file.
CLASS->instrument_runtime
Sets all available breakpoints to be either breakable or not. This
avoids making any part of the Enbugger:: or DB:: packages a part of
something that's visible to the debugger.
instrument_op( B::*OP )
A function that modifies B::COP objects.
DEPENDENCIES
A C compiler.
AUTHOR
Josh ben Jore >jjore@cpan.org<
COPYRIGHT AND LICENCE
Copyright (C) 2007 WhitePages.com, Inc. with primary development by
Joshua ben Jore.
This program is distributed WITHOUT ANY WARRANTY, including but not
limited to the implied warranties of merchantability or fitness for a
particular purpose.
The program is free software. You may distribute it and/or modify it
under the terms of the GNU General Public License as published by the
Free Software Foundation (either version 2 or any later version) and the
Perl Artistic License as published by O’Reilly Media, Inc. Please open
the files named gpl-2.0.txt and Artistic for a copy of these licenses.
POD ERRORS
Hey! The above document had some coding errors, which are explained
below:
Around line 259:
You forgot a '=back' before '=head2'